In modern high speed rotary web newspaper or the like printing presses, the webs from a plurality of printing units are assembled and directed into a folder mechanism where they are associated and combined to form complete products. As each succeeding product arrives at the folding cylinder, it is severed from the ensuing web whereupon it is tucked into the nip of second fold rollers to receive a transverse or cross fold prior to being deposited upon a delivery conveyor.
The second fold rollers must be capable of consistently and positively folding and advancing the products at high speeds and in order to reduce the probability of chokes occurring, i.e. two or more products becoming jammed between the rollers, they must be accurately spaced apart with direct relation to the thickness of the products. It is preferable that the space between the rollers be slightly less than the thickness of the products and that the control springs which bias the rollers to their operative position be set to exert a precise force against the rollers which is necessary to control and advance the products through the folding nip. The roller settings are relatively critical and they must be readjusted each time there is a change in the thickness of the products to be produced.
Although the prior art is replete with second fold roller mechanisms, all of the known devices have proved to be less than satisfactory for various reasons. Perhaps the most serious and common problem resides in the fact that whenever a space adjustment of the rollers is effected, it unavoidably changes the tension of the control springs which bias the rollers to their operative position. Consequently, if the space adjustment is rather substantial it is necessary to readjust the spring tension. Since the tension of the springs at each end of the rollers must be uniform and equal and moreover, because the tension adjusting members are usually relatively inaccessible, this is a tedious, time-consuming operation.
Another disadvantage of the known fold roller mechanisms resides in their objectionable, high noise level when in operation and the premature wear of the coacting elements. This is due to the fact that as each product passes through the fold roller nip, the rollers are forced apart against the tension of their biasing springs and a gap is thus created between the roller support members and their associated stops. Although such gaps are small, in most cases not exceeding a few thousanths of an inch, nevertheless as each product passes out of the nip, the rollers snap back to their preset position and the support members ram against the respective stops. Not only does this produce a loud clatter, but the constant pounding at high speeds results in distortion and premature wear of the control elements.